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Characteristics of surface and subsurface of formed thread parts by axial-infeed thread rolling process

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Chinese Journal of Aeronautics 2023年第3期36卷 471-481页

作者： Shuowen ZHANG Dawei ZHANG Shengdun ZHAO Fei JIANG Myoung-Gyu LEE Xi’an Key Laboratory of Intelligent Equipment and Control School of Mechanical EngineeringXi’an Jiaotong UniversityXi’an 710049China Department of Materials Science and Engineering Seoul National University08826 SeoulRepublic of Korea

The thread rolling process has been widely applied to manufacture high-performance thread parts.In this process,the evolutions of surface and subsurface are frequently introduced,which affect the working performance of manufactured parts.In this study,an axial-infeed thread rolling process(atrp)is employed,and the macro-meso surface characteristics under different lubrications and operating conditions are investigated.Moreover,the distributions of microstructure and hardness on the subsurface of formed tooth are analyzed in detail,along with the study of stress state and yield strength change.It is found that the MoS_(2)grease is more effective in reducing the surface roughness and defects than the lubrication oil and water-base graphite during the atrp process.Increasing rolling speed improves the quality of surface morphology and can reduce the surface roughness.On the subsurface of bottom and flank,intensive shear stress occurs in a narrow region,resulting in the elongation and refinement of the grains and increasing the low angle grain boundary fraction.Based on the grain size and plastic strain,the yield strength is predicted.The maximum yield strength and hardness on the bottom of formed tooth are improved by 41.2% and 39.4%,respectively.

关键词： atrp Lubrication Surface characteristics Microstructure distribution Hardness improvement Grain size

Synthesis of RNA-Amphiphiles via Atom Transfer Radical Polymerization in the Organic Phase

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Precision Chemistry

Precision Chemistry 2023年第5期1卷 326-331页

作者： Jaepil Jeong Grzegorz Szczepaniak Subha R.Das Krzysztof Matyjaszewski Department of Chemistry Carnegie Mellon UniversityPittsburghPennsylvania 15213United States Center for Nucleic Acids Science&Technology Carnegie Mellon UniversityPittsburghPennsylvania 15213United States University of Warsaw Faculty of Chemistry02-093 WarsawPoland

The combination of hydrophobic polymers with nucleic acids is a fascinating way to engineer the self-assembly behavior of nucleic acids into diverse nanostructures such as micelles,vesicles,nanosheets,and worms.Here we developed a robust route to synthesize a RNA macroinitiator with protecting groups on the 2′-hydroxyl groups in the solid phase using an oligonucleotide synthesizer.The protecting groups successfully solubilized the RNA macroinitiator,enabling atom transfer radical polymerization(atrp)of hydrophobic monomers.As a result,the RNA−polymer hybrids obtained by atrp exhibited enhanced chemical stability by suppressing cleavage.In addition,we demonstrated evidence of controlled polymerization behavior as well as control over the molecular weight of the hydrophobic polymers grown from RNA.We envision that this methodology will expand the field of RNA−polymer conjugates while vastly enhancing the possibility to alter and engineer the properties of RNA-based polymeric materials.

关键词： atrp RNA RNA-amphiphiles nucleic acid block copolymer RNA−polymer conjugate TBDMS SBiB phosphoramidite solid-phase RNA synthesis

atrp-Template Dispersion Polymerization of Methacrylic Acid/PVP

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Chinese Journal of Polymer Science 2014年第4期32卷 476-487页

作者： Cheng-cheng Yang Dan Meng Kan Zhan Yu-lu Chen Hui Zhang Min Wu 倪恨美 School of Chemistry and Chemical Engineering Southeast University

atrp-template dispersion polymerization of methacrylic acid （MAA） on the template of polyvinyl pyrrolidone （PVP K-30） was carried out in the aqueous solution by using methyl 2-bromopropionate （MBP）/CuC1/2,2＇-bipyridine （bpy） as the initiation system. The scanning electron microscopy （SEM）, dynamic light scattering （DLS） and gel permeation chromatography （GPC） were employed for evaluating the results of polymerization. As a result, the minimonomer droplets formed due to the H-bond interaction of PVP-MAA. The stability of droplets was dependent on pH and the concentrations of both PVP and MAA. When pH 〈 2, the coagulum of PVP-MAA formed, whereas when pH 〉 4.5, the droplets were not observable by DLS. In order to prepare the stable latex, the concentration of PVP should be lower than 9 wt%, whilst the concentration of MAA should be lower than 5.5 wt%. The optimum condition was pH 2.4, PVP 4.76 wt% and MAA 5 wt%, by which the stable latex of ca. 50 nm nanoparticles of PMAA/PVP was prepared by atrp polymerization and simultaneously the molar mass of PVP was duplicated by PMAA according to GPC diagrams. In contrast, by using AIBN, KPS and KPS-Na2SO3 redox initiation system, the coagulum accompanying with the larger molar mass of PMAA was obtained, irrespective of pH and concentrations of PVP and MAA.

关键词： Nanoparticle atrp Dispersion polymerization Template polymerization Hydrogel.

Synthesis of Membrane Adsorbers via Surface Initiated atrp of 2-Dimethylaminoethyl Methacrylate from Microporous PVDF Membranes

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Chinese Journal of Polymer Science 2014年第7期32卷 880-891页

作者： Tian Sun 张宇峰 Chun-lin Chen Xiang-zhuang Gong 孟建强 State Key Laboratory of Hollow Fiber Membrane Material and Membrane Process Tianjin Polytechnic University

Surface-initiated atom transfer radical polymerization （SI-atrp） was used to tether poly（2-dimethylaminoethyl methacrylate）（PDMAEMA） onto microporous PVDF membranes in order to synthesize membrane adsorbers for protein adsorption. The alkaline treatment and bromine addition reaction were used to anchor atrp initiators on membrane surface. Then PDMAEMA was grafted from the membrane surface via SI-atrp. Fourier transform infrared spectroscopy （FTIR）, X-ray photoelectron spectroscopy （XPS） and scanning electron microscopy （SEM） revealed the chemical composition and surface topography of the PVDF-g-PDMAEMA membrane surfaces. These results showed that PDMAEMA was grafted from the membrane surface successfully and a grafting yield as high as 1500 ~g/cm2 was achieved. The effects of the grafting time and the density of initiators on the static and dynamic binding capacity of bovine serum albumin （BSA） were systematically investigated. Both the static and dynamic binding capacities increase with the bromination and polymerization time. However, the benefits of the initiator density on binding capacities are limited by the graft density of PDMAEMA chains.

关键词： atrp PVDF membrane Protein adsorption Polyelectrolytes Graft polymerization.

Triphenylphosphine as Reducing Agent for Copper(II)-catalyzed AGET atrp

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Chinese Journal of Polymer Science 2015年第9期33卷 1260-1270页

作者：柏良久 Wen-xiang Wang Ming-hua Wang Jin-ming Sun 陈厚 School of Chemistry and Materials Science Ludong University

Triphenylphosphine （TPP） was used as reducing agent to continuously generate the Cu（I） activator in copper（II）- catalyzed activators generated by electron transfer atom transfer radical polymerization （AGET atrp）. For example, the polymers prepared with a molar ratio of [MMA]0/[EBiB]0/[CuC12]o/[PMDETA]0/[TPP]o = 500/1/0.1/0.5/0.5 had controlled molecular weights and low molecular weight distribution （Mw/Mn） values （-1.2）. TPP as a commercial reducing agent provides a convenient copper-catalyzed AGET atrp procedure for the preparation of well-defined polymers.

关键词： atrp AGET atrp Reducing agent Triphenylphosphine （TPP）.

INVESTIGATION OF THE atrp OF n-BUTYL METHACRYLATE USING THE Cu(I)/N,N,N',N",N"-PENTAMETHYLDIETHYLENETRIAMINE CATALYST SYSTEM

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Chinese Journal of Polymer Science 2004年第2期22卷 195-204页

作者： Kelly A. Davis Krzysztof Matyjaszewski Center for Macromolecular Engineering Department of Chemistry Carnegie Mellon University 4400 Fifth Ave.Pittsburgh Pennsylvania 15213 USACenter for Macromolecular Engineering Department of Chemistry Carnegie Mellon University 4400 Fifth Ave.Pittsburgh Pennsylvania 15213 USA

The polymerization of n-butyl methacrylate was investigated using the Atom Transfer Radical Polymerization technique with CuBr and CuCl/N,N,N',N',N'-pentamethyldiethylenetriamine catalytic systems. Various combinations of catalyst systems and initiators were utilized in order to optimize the polymerization conditions and to obtain well-defined polymers (i.e. controlled molecular weights and low polydispersities). It has been found that the optimal initiator for this system is a chlorine-based initiator, when the catalyst used is a salt in conjunction with the N,N,N',N',N'- pentamethyldiethylenetriamine ligand. Bromine-based initiators tend to result in large amounts of initial termination, leading to polymers with less than ideal chain end functionality, even if CuCl is used as the species to invoke the halogen exchange. Additionally, the effects of the polymerization temperature, species and the initiator structure were determined.

关键词： atrp Atom transfer radical polymerization Controlled/living radical polymerization Butyl methacrylate Pentamethyldiethylenetriamine

pH-responsive AIE-active Polyethylene-based Block Copolymers

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Chinese Journal of Polymer Science 2019年第9期37卷 930-935页

作者： Yu Jiang Nikos Hadjichristidis Physical Sciences and Engineering Division KAUST Catalysis Center Polymer Synthesis Laboratory King Abdullah University of Science and Technology (KAUST)

A novel synthetic strategy towards pH-responsive aggregation-induced emission (AIE)-active tetraphenylethene (TPE)- functionalized polyethylene-based block copolymers is presented. Tris(3-(4-(l,2,2-triphenylvinyl)phenoxy)propyl)borane was used to initiate the polyhomologation of dimethylsulfoxonium methylide to afford well-defined a-TPE-ω-OH linear polyethylenes (PE). The terminal hydroxyl groups were transformed to atom transfer radical polymerization (atrp) initiating sites by esterification with bromoisobutyryl bromide, followed by polymerization of rert-butyl acrylate (tBA) to provide TPE-PE-b-PtBA block copolymers. After hydrolysis of the rBu group to COOH group, the corresponding pH-responsive TPE-PE-b-PAA block copolymers were obtained. All synthesized block copolymers revealed AIE behavior either in solution or bulk. Due to the pH-responsivity of PAA chains, the aggregation state at different pH and consequently the fluorescence intensity changed. Also, the synthesized block copolymers exhibited ion-specificity fluorescence properties.

关键词： Polyhomologation atrp Polyethylene-b-poly(acrylic acid) AIE pH-responsivity Ion-specificity

Synthesis and Characterization of Butyl Acrylate-based Graft Polymers with Thermo-responsive Branching Sites via the Diels-Alder Reaction of Furan/Maleimide

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Chinese Journal of Polymer Science 2018年第9期36卷 1011-1018页

作者： Lin Ye Shao-Feng Zhang Yi-Chao Lin Jia-Kang Min LI Ma Tao Tang State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun 130022 China University of the Chinese Academy of Sciences Beijing 100049 China

Thermo-responsive butyl acrylate/furfuryl methacrylate copolymer-based （PBF backbone） graft （co）polymers with dynamic covalent linkages between their backbones and side chains via the Diels-Alder reaction of furardmaleimide were synthesized. Atom transfer radical polymerization （atrp） was used to synthesize graft copolymers with thermo-responsive transformation from graft copolymers to linear polymers with bimodal or wide MWD. The NMR measurements indicated that the Diels-Alder reaction and retro- Diels-Alder reaction occurred, depending on the change of the temperature, meaning that the side chains could be cleaved and reformed according to the variation of the temperature. GPC measurements demonstrated that the molecular weights of the polymers were thermo- responsive. Furthermore, three graft copolymers with various branching chains （PBF-g-PBA, PBF-g-P（BMA-co-MA） and PBF-g-PBMA） were compared to study the influence of compatibility between the backbone and the branching chain on the efficiency of Diels-Alder reaction after the cleavage of the DA linkage. The results showed that the ability of the side chains to come back to the main chain was strongly affected by the compatibility between the backbone and the side chains and the flexibility of the polymer chains.

关键词： Thermo-responsive Furan/maleimide atrp Diels-Alder Acrylate

ANTIFOULING PROPERTIES OF POLYVINYL CHLORIDE) MEMBRANES MODIFIED BY AMPHIPHILIC COPOLYMERS P(MMA-A-MAA)

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Chinese Journal of Polymer Science 2012年第4期30卷 568-577页

作者：朱宝库 Engineering Center of Membrane and Water Treatment Key Laboratory of Macromolecular Synthesis and Functionalization MOEDepartment of Polymer Science and EngineeringZhejiang University

Three well-defined diblock copolymers ofpoly（methyl methacrylate-b-methacrylic acid）（P（MMA-b-MAA）） were synthesized using atom transfer radical polymerization method and varying poly（methacrylic acid）（PMAA） chain lengths. These copolymers were blended with PVC to fabricate porous membranes via phase inversion process. Membrane morphologies were observed by scanning electron microscopy （SEM）, and chemical composition changes of the membrane surfaces were measured by X-ray photoelectron spectroscopy （XPS）. Static and dynamic protein adsorption experiments were used to evaluate antifouling properties of the blend membranes. It was found that, the blend membranes containing longer PMAA arm length showed lower static protein adsorption, higher water permeation flux and better protein solution flux recovery.

关键词： Amphiphilic copolymer atrp Poly（vinyl chloride） Antifouling property P（MMA-b-MAA）.